There are recipes on the internet (Google on render chicken fat). The first one I looked at I wouldn't follow at all. It added water and then required straining. It made it too complex. The next one has good photos, but it too added water. I don't add water at all. Oil and water don't mix. But my method requires low heat, more attention and stirring. Just take the fat, cut it up with a scissors, and throw it in a sauce pan. Then use a low to medium heat to get it going. Stir it (and perhaps press it) until the oil starts coming out and then it won't stick to the pot. After that, let it cook down with occasional stirring. It won't take too long for a small amount. Maybe 10–15 or maybe 15–30 minutes depending on amount. You don't need high heat and you shouldn't fry or burn the fat. All you're doing is melting out the fat. I've gone away and forgotten about it sometimes, reminded only when I heard it popping. No great harm was done to it, but you really want it to be just a light golden color, not burnt brown. Pour off the oil. When it cools, it congeals. You can then use it as a spread, with a little salt. Or you can use it in matzo balls. You use it in your chopped or fried chicken liver too. It's the only thing that's right for these. Ah-hah. Now I've finished writing this and I find the best recipe corresponding to mine. They add some onion, yes, that helps and then you get some grieben too. (Check Google for that.)
My memory wasn't bad on aging beef. I've found a professional chef who says 6 weeks. Yes, that's about it. We'd wrap it up and seal it tightly in steak paper thoroughly. This is called wet-aging. We'd leave it in the meat cooler where the temperature was about 38 to 40. You need a big piece. You cannot do individual steaks because you'd end up trimming too much that may be spoiled. The aged piece may require some trimming of the outside, but the inside should be OK. You can see the problem. You may need a whole shelf of an ordinary refrigerator to attempt this. Got a spare in the garage? That might work well. This is a risky business. A whole boneless loin costs a pretty penny. Maybe your friendly neighborhood meat merchant will do it for you.
If you find a good kosher salami, you can age it by hanging it up in your cool and dark basement until it starts to dry up and shows indentations. This can take about 8–12 weeks. You will get real hard salami, not what is called hard salami in stores. It will be more like beef jerky. In Chicago, the best source of salami (and real corned beef) I know of is Sinai 48 for kosher salami (100o W. Pershing). I doubt that anything good will come of using a supermarket's product.